An ubiquitous network refers to the network in which a subscriber can be provided with various broadband services such as Internet, an Internet protocol IP communications, by connecting to a network in anytime, anywhere. For instance, the ubiquitous network has a mobile radio communications network. While mobile communications network subscribers can talk over the telephone with a desired person in anytime, in anywhere by using a mobile phone, recently, they can be variously provided with the internet connection and application services.
However, the mobile radio communications network is configured as telephone network according to the voice communications of the narrow band. Therefore, there is a limit in configuring the ubiquitous network by using the mobile radio communications network. That is, there is a problem in that the broadband service is limited in providing the service since the mobile radio communications network has the limit of the frequency bandwidth for providing the internet service, and a considerable cost has to be paid due to the use of the expensive frequency channels.
A portable Internet has appeared so as to solve such a problem. The portable Internet can provide the internet access service of broadband with low cost. The portable Internet introduced the concept of a home agent in which a terminal was subscribed and a foreign agent in order to have a portability. In normal cases, the terminal accesses to the home agent, and the home agent performs the routing processing for the packet sent to the terminal and received from the terminal. In the mobile environment, the terminal accesses to the foreign agent. However, the foreign agent performs the role of only transferring the packet of the terminal to the home agent. In conclusion, the home agent processes all packets.
However, as to such mode, the radio communications between a base station and a mobile terminal is focused, but the cable communications between them is not dealt at all. In addition, the home agent and all foreign agents are to be connected to the wired channel. Therefore, the technical matters of the wired network side have to be solved in order that logical tunnels between all agents are formed and agents can be connected by cable.